Circumferentor or surveyor’s compass
- maker:
- George Adams
Circumferentor or surveyor's compass probably used on the survey of the Mason-Dixon line
This circumferentor or surveyor's compass was made by George Adams of London, one of the top instrument makers of the day. It is believed to have been used by British surveyor Jeremiah Dixon to measure horizontal lines during the Mason–Dixon survey in colonial North America (1763–1767). This surveying expedition was aimed at settling a border dispute between the Penn and Calvert families who governed the colonies of Pennsylvania, Delaware and Maryland.
The instrument is inscribed in an engraved circle; 'Geo: Adams LONDON'. Circumferentors (with a full circle scale) and graphometers (with a half circle scale) were widely used for angle measurement in the 17th and 18th centuries. A joint on the support allowed for both vertical and horizontal use.
Details
- Category:
- Surveying
- Object Number:
- 1977-755
- Materials:
- brass, steel, blued, needle and silver, scale in compass
- Measurements:
-
radius (circle): diameter 150 mm
compass: height 155 mm
- type:
- circumferentor
- rights:
- Unlinked Name
- credit:
- Royal Geographical Society